1,3-Butadiene (BD) is an important building block used in the polymer chemistry. It is used among other things in the production of styrene-butadiene rubbers that are primarily used in the fabrication of materials such as synthetic rubber or elastosmers which make up products such as production of polymers such as synthetic rubbers or elastomers including styrene-butadiene rubber (SBR), polybutadiene rubber (PBR), nitrile rubber (NR) and polychloropropene (Neoprene).
Currently, BD is typically primarily obtained as a by-product of the naphtha steam cracking process that serves to make ethylene. The production of ethylene from steam cracking is in decline due to the recent and drastic increase of shale gas production in the USA which offers another pathway for obtaining ethylene from ethane but does not result in the BD creation. In addition to the shift in lighter feedstocks, crude oil price swings have historically led to corresponding price fluctuations in the cost of butadiene, and this is not sustainable for the end users of this important building block. Thus, alternative technologies for producing butadiene are highly desired.
Ethanol conversion to butadiene (ETB) represents an attractive alternative technology. Ethanol can be sourced from a variety of locations including commercial production from renewable biomass or waste sources. In addition, the ethanol “blend wall” coupled with advancements in production efficiency and feedstock diversification will potentially lead to excess ethanol at competitive prices available for the production of a wide range of fuels and commodity chemicals. Furthermore a recent early-stage assessment method comparing the bioethanol-based pathway for butadiene production with the naphtha-based route suggests that the bioethanol pathway could be a promising alternative to the naphtha-based process.
Research on butadiene production from ethanol has existed for years however, achieving high yield to butadiene at industrially relevant process conditions has been challenging. There are a large number of catalyst systems capable of converting ethanol to butadiene in one step that have been reported however, in many of these instances low single pass conversion (<45%) resulted. For the single-step process to be successful and viable higher per pass conversion and high selectivity (≥70%) are desirable. What is needed is a system for producing BD from ethanol that can achieve this higher selectivity in a single pass. The present disclosure provides examples of advances toward meeting this need.
Additional advantages and novel features of the present invention will be set forth as follows and will be readily apparent from the descriptions and demonstrations set forth herein. Accordingly, the following descriptions of the present invention should be seen as illustrative of the invention and not as limiting in any way.